CVE-2018-6930 in ImageMagick
Summary
by MITRE
A stack-based buffer over-read in the ComputeResizeImage function in the MagickCore/accelerate.c file of ImageMagick 7.0.7-22 allows a remote attacker to cause a denial of service (application crash) via a maliciously crafted pict file.
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Analysis
by VulDB Data Team • 02/06/2023
The vulnerability identified as CVE-2018-6930 represents a critical stack-based buffer over-read condition within ImageMagick's image processing library, specifically affecting version 7.0.7-22. This flaw exists in the ComputeResizeImage function located within the MagickCore/accelerate.c source file, making it susceptible to remote exploitation through crafted pict format files. The vulnerability stems from inadequate input validation and memory boundary checking during image processing operations, creating a scenario where maliciously constructed image data can trigger unintended memory access patterns that exceed allocated buffer boundaries.
The technical implementation of this vulnerability demonstrates a classic buffer over-read exploit pattern that operates through the image processing pipeline when handling pict format files. When ImageMagick attempts to resize images using the ComputeResizeImage function, it fails to properly validate the dimensions and memory requirements of the input data, allowing an attacker to craft a pict file that causes the application to read beyond the allocated stack memory space. This condition manifests as an application crash or denial of service, as the program attempts to access memory locations that are either unmapped or contain unrelated data. The flaw operates at the memory management level, where the stack buffer allocation does not account for potentially malicious input values that could cause the read operation to extend beyond the intended memory boundaries.
From an operational impact perspective, this vulnerability creates significant security concerns for systems that rely on ImageMagick for image processing, particularly those exposed to untrusted user uploads or remote file processing. The remote exploitation capability means that attackers can trigger the denial of service condition without requiring local access or authentication, making it particularly dangerous in web applications, content management systems, or any platform that processes user-uploaded images. The vulnerability affects the availability of services since legitimate image processing operations may be disrupted by a single malicious file, potentially allowing for sustained denial of service attacks against image processing services. Organizations using ImageMagick in production environments face risks of service interruption and potential resource exhaustion if not properly mitigated.
The vulnerability aligns with CWE-125, which specifically addresses "Out-of-bounds Read" conditions in software systems, and demonstrates how improper input validation can lead to memory safety issues in image processing libraries. From an attack perspective, this flaw maps to ATT&CK technique T1203, where adversaries exploit software vulnerabilities to cause system instability or denial of service conditions. The exploitation requires minimal privileges and can be automated, making it particularly attractive to threat actors seeking to disrupt services or establish persistent access through system instability. Organizations should implement immediate mitigations including updating to patched versions of ImageMagick, implementing input validation controls, and deploying network-based protections to prevent unauthorized access to image processing endpoints. Additionally, organizations should consider implementing sandboxing mechanisms and restricting image format support to reduce the attack surface and prevent exploitation of similar memory safety vulnerabilities in related components.